.TH GATE 8 "12 Mar 2020" "iproute2" "Linux"
.SH NAME
gate \- Stream Gate Action
.SH SYNOPSIS
.B tc " ... " action gate
.ti +8
.B [ base-time
BASETIME ]
.B [ clockid
CLOCKID ]
.ti +8
.B sched-entry
<gate state> <interval 1> [ <internal priority> <max octets> ]
.ti +8
.B sched-entry
<gate state> <interval 2> [ <internal priority> <max octets> ]
.ti +8
.B sched-entry
<gate state> <interval 3> [ <internal priority> <max octets> ]
.ti +8
.B ......
.ti +8
.B sched-entry
<gate state> <interval N> [ <internal priority> <max octets> ]

.SH DESCRIPTION
GATE action allows specified ingress frames can be passed at
specific time slot, or be dropped at specific time slot. Tc filter
filters the ingress frames, then tc gate action would specify which time
slot and how many bytes these frames can be passed to device and
which time slot frames would be dropped.
Gate action also assign a base-time to tell when the entry list start.
Then gate action would start to repeat the gate entry list cyclically
at the start base-time.
For the software simulation, gate action requires the user assign reference
time clock type.

.SH PARAMETERS

.TP
base-time
.br
Specifies the instant in nanoseconds, defining the time when the schedule
starts. If 'base-time' is a time in the past, the schedule will start at

base-time + (N * cycle-time)

where N is the smallest integer so the resulting time is greater than
"now", and "cycle-time" is the sum of all the intervals of the entries
in the schedule. Without base-time specified, will default to be 0.

.TP
clockid
.br
Specifies the clock to be used by qdisc's internal timer for measuring
time and scheduling events. Not valid if gate action is used for offloading
filter.
For example, tc filter command with
.B skip_sw
parameter.

.TP
sched-entry
.br
There may multiple
.B sched-entry
parameters in a single schedule. Each one has the format:

sched-entry <gate state> <interval> [ <internal priority> <max octets> ]

.br
<gate state> means gate states. 'open' keep gate open, 'close' keep gate close.
.br
<interval> means how much nano seconds for this time slot.
.br
<internal priority> means internal priority value. Present of the
internal receiving queue for this stream. "-1" means wildcard.
<internal priority> and <max octets> can be omit default to be "-1" which both
 value to be "-1" for this <sched-entry>.
.br
<max octets> means how many octets size could pass in this time slot. Dropped
if overlimited. "-1" means wildcard. <max octets> can be omit default to be
"-1" which value to be "-1" for this <sched-entry>.
.br
Note that <internal priority> and <max octets> are nothing meaning for gate state
is "close" in a "sched-entry". All frames are dropped when "sched-entry" with
"close" state.

.SH EXAMPLES

The following example shows tc filter frames source ip match to the
192.168.0.20 will keep the gate open for 200ms and limit the traffic to 8MB
in this sched-entry. Then keep the traffic gate to be close for 100ms.
Frames arrived at gate close state would be dropped. Then the cycle would
run the gate entries periodically. The schedule will start at instant 200.0s
using the reference CLOCK_TAI. The schedule is composed of two entries
each of 300ms duration.

.EX
# tc qdisc add dev eth0 ingress
# tc filter add dev eth0 parent ffff: protocol ip \\
           flower skip_hw src_ip 192.168.0.20 \\
           action gate index 2 clockid CLOCK_TAI \\
           base-time 200000000000ns \\
           sched-entry open 200000000ns -1 8000000b \\
           sched-entry close 100000000ns

.EE

Following commands is an example to filter a stream source mac match to the
10:00:80:00:00:00 icmp frames will be dropped at any time with cycle 200ms.
With a default basetime 0 and clockid is CLOCK_TAI as default.

.EX
# tc qdisc add dev eth0 ingress
# tc filter add dev eth0 parent ffff:  protocol ip \\
	flower ip_proto icmp dst_mac 10:00:80:00:00:00 \\
	action gate index 12 sched-entry close 200000000ns

.EE

.SH AUTHORS
Po Liu <Po.Liu@nxp.com>
